Moving or changing advertising and display apparatus or sign



1 J. WHITFIELD ET AL 1,389,302

MOVING OR CHANGING ADVERTISING AND DISPLAY APPARATUS OR SIGN Original Filed Jan. 17. 1930 4 Sheets-Sheet 1 Q 1932- J. WHITFIELD ET AL 1,889,302

MOVING OR CHANGING ADVERTISING AND DISPLAY APPARATUS OR SIGN Original Filed Jan. 17, 1930 4 Sheets-Sheet 2 IN YEA/TOR:

Nov. 29, 1932. 1,889,302

MOVING 0R CHANGING ADVERTISING AND DISPLAY APPARATUS OR SIGN J. WHITFIELD ET AL Original Filed Jan. 17, 1930 4 SheetsSheet 3 v v 2 f H 0 a4 a, x 4. HT I w H 9N 1 m I L F mm z E 1 a H w a L T u I/ J w n a F m h n m E m 9 u a n u m E r. J r 1 NOV. 29, wH T l LD ET AL MOVING OR CHANGING ADVERTISING AND DISPLAY APPARATUS OR SIGN Original Filed Jan. 17. 11950 4 Sheets-Sheet 4 uvvzwrons .1 WHITF/fLD m a. 094N050 Patented Nov. 29, 1932 PATENT orrice JOHN WHITFIELD AND DAVID BRANDER, OF GLASGOW, SCOTLAND MOVING R CHANGING ADVERTISING AND DISPLAY APPARATUS OR SIGN Application filed. January 17, 1930, Serial No. 421,559, and in Great Britain January 31, 1929.

Renewed April 28, 1932.

This invention relates to moving, or changing, advertising and display apparatus, or signs, and refers more particularly to such apparatus carrying advertisement matter of the type comprising a band carrying the advertisements, or display matter, wound on to and ofi magazine rollers adapted to be moved intermittently by an electric solenoid or like device so as to display a complete new ad- 19 vertisement and/or a complete new indication at each operation of said device, the movement being continued until the band is wound off one magazine roller on to the other, to complete a cycle and thereafter reversed.

For many reasons, it is not only desirable that the sign should be of a moving nature, so that, for instance, in the case of advertise ments, a-greater number of advertisements or a larger advertisement can be displayed for a given space than is possible with a fixed sign, but, also, that its movement is entirely automatic so that, once started, it will function without any discontinuity or attention until it is stopped. r

The object of the present. invention-is to provide moving or changing, advertising and display apparatus or signs which will be compact in arrangement and efficient in operation and which will be adapted to displaydifier- 39 cut advertisements or representations in succession. A further object is to provide an automatic method of operating such apparatus or signs.

A further object of the invention is to provide a moving or changing, advertising or display apparatus or. sign in which a series of diitcrent representationsor advertisements are displayed successively from an intermittently moving band, and a still further object is to provide such an apparatus or sign in which the display band. is automatically reversed at the end of its intermittent motion in one direction.

Further objects will appear throughout the specification. J

The apparatus providedaccording to the present invention 'm'ay, comprise, in .combination, circuit controlling means, driving means for moving the band carrying the matter to be displayed or advertised, means adapted to permit-a limited amount of that movement to take place, means adapted to act on said circuit controlling means causing it to open its circuit to render said driving means inoperative, and means associated with said driving means for causing said circuit controlling means to closeits circuit again. Means may be provided for automatically reversing the movement communicated by the driving means to the band. And means may alsobe provided for adjusting thetimeduring which'an advertisement or display is on view. In addition, when a display band is passed between two rollers, we provide means for compensating for change in the effective diameter of these rollers as the hand is wound from one to the other.

We will. now describe one embodiment of our invention simply by way of example, with reference to the accompanying drawings these illustrate automatically operating apparatus for displaying a series of representations successively, each representation being displayed forv a predetermined time in terval.

On the drawings Fig. l is a rear elevation of the complete. apparatus located in a casing, the rear wall thereof being removed for the sake of clearness. 7

Fig. 2 is a side elevation taken in the directionof the arrow II, Fig. 1.

Fig. 3 is a detail sectional view of the time lag solenoid hereinafter described, to an enlarged'scale.

Figs. 4 and 5 are respectively detail plan view and side elevation in the direction of the arrow V, of the gearing for driving the band carrying the representations, the mechanism for intermittently locking the display band against movement, and for reversing the movement of the same, drawn to an enlarged scale. 7

. Fig. 6 is an enlarged part sectional elevation of the main solenoid and the automatic circuit'bre'aking means, looking in the reverse'direction from Fig. 2.

Fig. 7 is a fragmental sectional view to an enlarged scale, of one end of one of the magazine rollers which carry the display band.

Fig. 8 is a diagrammatic fragmental View of the magazine, driving and guide rollers over which the display band passes, and also shows the compensating driving gearing for the magazine rollers.

Fig. 9 is a circuit diagram of the electrical connections in the apparatus.

Fig. 10 is a detailed View onthe line w-w, Fig. 4, illustrating the pawl and ratchet devices 59, 61, and 60, 62, hereinafter referred to. I

Fig. 11 is a detailed view on the line XI-XI, Fig. 1, illustrating the dashpot 37, hereinafter referred to.

In outline, the apparatus comprises a time lag solenoid device T adapted to close the main circuit to bring the various component mechanisms of the apparatus into operation, a main solenoid device'M' adapted to move the display hand through mechanism to be described, an unlocking solenoid device U which normally locks the main drive shaft for the band against movement, but intermittently unlocks the same, to permit movement, and a pair of reversing magnets R for reversing the general direction of movement of the band after it has been completely passed in one direction.

The time lag solenoid T comprises a winding 10 (Fig. 3) and a plunger 11 which is adapted to beraised against the action of a spring 12 anchored at its upper end to the frame 13 of the solenoid. By reason of the illustrated mode of connecting the plunger 11 to its upper extension 11 which passes through the guide bush 21, smooth movement of the plunger is assured. Motion of the plunger 11 in the upward direction is retardedby the piston 15 attached to its lower end and which slides in the dashpot cylinder 14; inflow of air to this cylinder-is controlled by the adjustable needle valve 16; by varying the restriction of the passage of this valve, the time which the plunger 11 takes to rise can be controlled. In order to ensure quick fal ing motion of the plunger a free ball valve 17 is provided, and this only opens when the piston and plunger are falling After rising for a certain time interval, the duration of which is controlled by the needle valve 16, the carbon ring 18, secured to the plunger, closes the main circuit through the two contacts 19, 19

The closure of the main circuit excites the main and unlocking solenoids, which are con- Near the commencement of the upward motion of the main solenoid plunger 22, it short circuits the unlocking solenoid winding by means of the conducting element 27 which is fitted in the frame 23 and moves with it, but is insulated from it. The frame 23 is secured to the plunger 22, and as it moves upward with it, the element 27 closes a circuit between two contacts 28, 28 (only one 28 of which is visible in the drawings) which short-circuits the unlocking solenoid winding. The contacts 28, 28 are secured to the member 29 which is fixed relativeto the frame 23.

Towards the end of the upward stroke of the main solenoid plunger 22, the time lag solenoid winding is broken. The adjustable rod 30 moves upward with the frame 23 and tilts the bell crank lever 31 clockwise (Fig. 6) about the pivot 31*, whereby the link 32 moves outwardly and tilts the depending lever 33 anti-clockwise (Fig. 6) against a spring 36 and about its pivoting point 33 whereby the time lag solenoid energizing circuit, normally made between the contacts 34 and 35, is broken. On the downward movement of the main solenoid plunger 22 and rod 30, the lever 33 is gradually returned to its normal position, by means of the spring 36 acting against the dash-pots 37, to close the time lag solenoid circuit. The arrangement of each dashpot 37 is shown in Fig. 11, the connecting rod of the leather piston 37 being connected to the lever 33 by a ball joint 37 the connecting rod passing through clearance holes in the frame member 23, and the lever 33. A restricted orifice 37, in the dashpot 37, controls exit and ingress of air. By controlling the exit of air from the dashpots 37, the time taken for the contacts 34, to close, during the return of the plunger 22, can be adjusted.

As aforesaid, at the same time as the main solenoid is energized, so is the unlocking solenoid; this unlocking solenoid is mounted close to the reversing solenoids, and all will be described together with reference to Figs. 4 and 5.

The numeral 38 represents the unlocking solenoid winding, 39 is the frame, and 40 is a rod adapted to be actuated by the upper end of the plunger of this solenoid. The rod 40 is attached to a locking bar 41 adapted to engage with any of a number of slots 42 in the periphery of a disc 43 secured to the main shaft 44 which transmits the drive from the main solenoid plunger to the display band driving roller. Normally the rod 40 is ield down (that is, to the left Fig. 5) by a spring 4O (Fig. 1) so keeping the bar 41 in engagement with one of the slots 42, thereby locking the main shaft against movement; when the winding is energized the extension is moved upwardly and frees or unlocks the main shaft. When the winding is de-energized, the bar 41 falls down upon the periphery of the disc 43 and engages the next slot 42 when it has turned into-the correct position.

From the above it will be evident that, if

the main solenoid and unlocking solenoid are actuated intermittently more or less in synchronism, an intermittent drive will be communicated to the display band.

In order to reverse the direction of movement of the display band when it has been completely passed between its magazine rollers in one direction, either of the reversing magnets 45,46,is selectively energized,whereby one of the plungers 45 46 is pulled downwardly into its magnet, whereby the T-lever 457 is tilted, about its pivot at 95, by one of the links 4.8. Tilting of this lever 47 causes the lever 49 (ghost view Fig. 4-) to turn about its fixed pivot 50. Two pins 51, 52 are fitted to the underside of this lever 49, and bear on sleeves 53, 54- freely turnable and slidable on shafts 55, 56 respectively. Each sleeve 53, 54 has formed integral therewith a pinion 25 or 26 respectively, in continuous engagement with the corresponding toothed surface 24* or 24; of the rack 24. Each pinion 25, 26

has pivoted thereon a pawl, detent or other engaging member 59, 60 adapted tobe moved into or out of engagement with a corresponding ratchet or toothed wheel 61, 62, in accordance with the movement communicated to the sleeves 53, 54 by thelever 49. Each of these wheels 61, 62 is secured to a shaft or 56 carrying a corresponding bevel wheel 63, 64:, each of which is in engagement with a corresponding bevel wheel 65, 66 secured on the main display band driving'shaft 4%. It will thus be evident how excitation of either of the reversing magnets causes the drive from the main solenoid. to pass through either of the unidirectional clutches, comprising the pawl and ratchet wheel 62 or the pawl 59 and ratchet wheel 61', to themain shaft. The motion communicated to the main shaft through either of these gear trains, is in the reverse direction to that communicated through the other. In Fig. 10 the pawl and ratchet device 59, 61, is shown in detail. The surface 2% of the rack 24, is shown in engage ment with the pinion 25, which carries an arm 25 towhich is pivoted a pawl 59, engaging the ratchet wheel 61. The pawl 59 is held in its correct position abutting on the stop 59, by means of the spring 59". The pawl and ratchet device 60, 62, is similar.

In Fig. 5 the lever 49 is in a different posi tion to that in Fig. i; it is in the midway position with the Tlever 47 untilted. Actually the bar 49 is arranged to remain in either of its extreme positions until the reversing mechanism comes into action and changes it over.

The numeral67 represents the main drive ing wheel for the display band 94. This wheel 67 gears with a pinion 68 secured to the spindle of theband driving roller 69, and

socommunicates the drive to this roller; a bevel pinion 70 (Fig. 8) is also secured to the spindle of the roller 69, and by means of this the drive is communicated through the shafts 71, 72 and other bevel gearing to each of the magazineirollers 73, 7 4 upon and from which the display band is alternately wound. As shown, in passing from the temporarily unwinding magazine roller 73, the band passes over a roller 7 5, then passes around the drivingroller 69, then along the display front of the apparatus and then over a guide roller 76 before passing to the temporarily unwinding magazine roller 74.

It will be evident that, assuming the roller 73 isfully wound and the roller 7 4 fully unwound, and assuming that these rollers are equally geared from the driving Wheel 67, assuming thebevel wheel 70 is of the same diameter as the bevel wheels 7 3, 74?, when the band starts to move, in the first place the roller 73 will tend to give off more paper than the roller 74 can wind on for the same speed of revolution; in the second place, due to the relative change in diameter of the paper on the roller, when the roller 73 has been more than half unwound, the reverse will take place, the roller 74 tending to wind on more paper than the roller 73 can unwind.

In order to compensate the motion of the magazine rollers for these changes,we provide the mechanism illustrated in Figs. 7 and 8. Each magazine roller 73, 74 is provided with unidirectional: clutching means through which either the drive can be communicated direct to'the roller, or the roller is permitted to rotate freely. Each unidirectional clutching means comprises a drum 77 having peripheral apertures 78 thereon each of which carries freely therein a roller 79. When the drum 77 tends to move clockwise (Fig.8) relative to its rollers, it moves freely, withoutdriving the magazineroller, the rollers 79 each turning freely in the larger end of its aperture 78 when however, the drum 77 tends to' move anti-clockwise (Fig. 8) relative to its magazine roller, the rollers 79 are each jammed tightly between the drum and magazine roller at the small end of its aperture 78 and impart a positive drive to the magazine roller. Similarly, when a magazine roller tends to turn anti-clockwise (Fig. 8) relative to its drum 77, it does so freely but if it tends to turn in the other direction it clutches the drum. In addition to the mechanism just described, each of the magazine rollers is provided with a friction clutch (Fig. 7) located between the bevel pinion on its spindle and the unidirectional clutching device. Each friction clutch comprises a member 81 secured to the bevel pinion 7 3 or 7 4 and having a frictional surface co-operating at 83 with a frictional surface on the drum 77. The drum 77 is free on the spindle 84 or 85 of the magazine roller 73 or 74 but can communicate the drive thereto by means ofthe aforesaid unidirectional clutching device. Further, the bevel pinion 7 O is of greater diameter than the bevel pinion In the movement of the hand between the magazine rollers two circumstances can arise, firstly, when the band is being wound from the rollers 73 to the roller 74, and secondly, when it is being wound from the rollers 74 to the roller 73. In the first case, assuming the rotation of the driving roller 69 to be clockwise (see arrow, Fig. 8). the magazine roller 74 is turned anti-clockwise to wind on the band, and due to the unipinion and the bevel pinions 73 and 74 Owing to the positive geared up drive com municated to the roller 74 it always tends to take more of the display hand than the drivingfroller v69, of constant diameter, delivers to it, but this difference is taken up by slipping in thefriction clutch on the roller 74. Further, owing to the geared up drive communicated to the drum 77 of the roller 73, no matter how much the diameter of the band on the roller is reduced (and the speed of the roller is consequently increased by the direct pull on the band from the driving roller 69), the drum is always rotated faster than the roller and consequently the latter runs freely throughout the whole of the unwinding operation. In addition the linear speed of the whole band is maintained constant by the driving roller 69 which engages with the display band.

Obviously the relative diameter of the bevel pinions 70, and 7 3 74 will have to be increased if the length of the display band is increased.

When the movement of the display band is reversed the driving roller rotates anti-clockwise (Fig. 8) and the change in the effective diameters of the rollers 7 3 and 7 4 is compen sated in similar manner to that just described, slipping taking place this time in the friction clutch of the roller 73. a

The driving roller 69 keeps in driving engagement with the display band by means of a peripheral row of pins 94 adapted to engage a series of corresponding holes 95 running along the edge of the band. Owing to the number of pins always engaging, the band is not subjected to great wear.

In order automatically to reverse the movement of the display band when it is unwound in either direction, slots are provided in the band, near the end thereof. Now, when these slots pass over the jockey roller 75, contact is permitted between two of the three metal contact'rollers 86, 87, 88 and the roller 7 5 which is itself provided with "a metallic sleeve 89 (Fig. 9). Normally the contact rollers are insulated from this sleeve by the display band which passes between them. The slots at the two ends of the band are placed so that a different pair of rollers make contact according to which end of the band is approaching. The contact of the pair of rollers with the aforesaid sleeve closes the circuit of one of the reversing magnets 45, 46 (Fig. 5) in order to bring the reversing mechanism shown in Fig. 4 into operation. This reversing mechanism has already been described.

Fig. 9 shows the diagram of electrical connections the whole apparatus being brought into action by the operator closing the main switch S, after which the apparatus functions automatically.

Lighting means such as an electric lamp 91 are placed behind the display band in order clearly to display the matter thereon.

In operation, the closure of the main switch S closes the circuit of the time lag solenoid through the contacts 34, 35. After the plunger 11 has risen for a time interval controlled by means of the dashpot 14, the circuit containing the unlocking solenoid U and main solenoid M in series is closed at the contacts 19, 19; this causes the main driving shaft 44 to be unlocked by the unlocking solenoid and at the same time drives the main shaft 44 by means of the main solenoid plunger 22-. As the plunger 22 rises it first short circuits the unlocking solenoid through the contacts 28, 28*, and then, near to the top of its travel it opens the main circuit through the contacts 34, 35, thereby deenergizing the time lag solenoid the plunger 11 of which on falling opens the main solenoid circuit, thereby also allowing the plunger 22 and the rack to fall. This reversing movement of the rack is not communicated to the main shaft 44 owing to the interposition of the pawl and ratchet devices 59, 61, and 60, 62. When the unlocking solenoid is short-circuited its plunger falls and so also does the locking bar 41, and the latter rides on the periphery of the disc 43 until the next slot 42 arrives, whereupon it engages it and so limits the rotation of the main shaft to a predetermined amount.

When the main solenoid is de-energ'ized its plunger 22 falls and so permits the contacts 34, 35, to close again, but this closure is retarded by the dashpot 37 6), the action of which can be controlled. lVhen the contacts 34, 35, do close again, they remake the main circuit, energizing the time lag solenoid again, and the whole cycle of operations is repeated again. The duration of the time interval for which the matter on the display band is displayed, is controlled by the time taken for the contacts 34, 35, to close and for the plunger 11 to rise and remake the main solenoid circuit.

The circuit containing the reversing magnets is in parallel with the main circuit through the contacts34, 3 5, and is only closed ready for operation, when the plunger 22 is at the bottom of its stroke and the element 92 on the frame 2.3 closes the circuit through contacts 93, 93 i It will be understood that-the size, con,- struction and arrangement of the apparatus will vary with the nature of the Imatter-being displayed and the uses to which it is put, and, a so, t atany of the pa t c n be duplicated or otherwise increased in number or relative size according to requirements; for instance, in the case of a large automatic sign, whence large amount of the display band has to :be moved, the number of solenoids nay beincreased and these solenoids arranged to .ccme into action successively.

In practice, we have found linen faced paperor ordinary paper tobe suitable forthe display band.

We claim:

1. In advertising or display apparatus of thetype referred to, the combination of, a display band ,carryingthe matter to be d splayed or advertised, an electric circu tcontrolling solenoid, a solenoid device for moving the band carrying the matter to bevdis played or advertised, driving mechanism through which the display band is driven from saidsolenoid device, an unlocking device for temporarily unlocking said driving mechanism which is normally locked against rotation by said solenoid device, thereby allowing movement of said band to take place, and automatic means for rendering inoperativesaid solenoid device for moving the band.

In advertising or display apparatus of the type referredto, the combination of, a display band carrying the matter to be displayed or advertised, amain electric circuit, atimelag solenoid device adapted to make or break said main circuit, a main or band driving solenoid device in said main circuit adapted to move said display band, driving mechanism through which the display band is driven from said band driving solenoid device, an unlocking solenoid device in said main circuit adapted temporarily to unlock said driving mechanism which is normally locked against rotation by said unlocking solenoid device, and contact breaking means associated with said main solenoid device for breaking said main circuit and de-energizing said time lagsolenoid device.

3. In advertising or display apparatus of the type referredto, the combination of, a display {band carrying the matter to beidisplayed or advertised, a main electric circuit, a time lag solenoid device adapted to make or break said main circuit, a main or band driving solenoid device in said main circuit adapted to move the display band, an unlocking solenoid device in said main circuit comprising an unlocking solenoid adapted to lock and unlock intermittently the drive for the display band in order to permit intermittent movement of said band by a predetermined amount, and contact breaking means associated with said main solenoid device for breaking said main circuit and de-energizing said time lag solenoid device.

4:. In moving or changing advertising or display apparatus, the combination of, a main electric circuit, a movable display band carrying the matter to be displayed or advertised, a time lag solenoid device for controllingthe opening and closing of said maincircuit, driving means in said main circuit for moving the display band, an unlocking solenoid device in said main circuit adapted temporarily to unlock a part of the apparatus normally looked thereby against rotation and permit movement of said band by a pre-determined amount, contact means adapted to'be opened by said driving means after a predeterminedinterval in order to open the circuit of said time lag solenoid thereby causing said time lag solenoid thereby to open said main circuit and render said driving means inoperative, said contact means reclosing when said driving meansbecomes inoperative thereby reclosing the circuit of the time lag solenoid, which after a predetermined in.- terval recloses the main circuit.

' 5. In moving or changing advertising or display apparatus, the combination of, a main electric circuit, a movable display band carrying the matter to be displayed or advertised, a time lag solenoid device for controlling the opening and closing of said main circuit, driving means in said main circuit for moving the display band, an unlocking solenoid device in said main circuit adapted temporarily to unlockapart of the apparatus normally locked thereby against rotation and permit movement of said band by a predetermined amount, contact means adapted to be opened by said driving means after a predetermined interval in order to open the circuit of said time lag solenoid thereby opening said main circuit and rendering said driving means inoperative, said contact means reclosing when said driving means becomes inoperative thereby reclosing the circuitof the time lag solenoid, which after a predetermined interval recloses the main circuit, a pair of electromagnetsone of which is adapted selectively to be energized through a circuit completed through an aperture in the display band after said bandhas been wound up in one direction.

' 6 Inadvertising or display apparatus of thetype referred to, the combination of, a display band carrying thematter to be displayed or advertised, a main'electric circuit, a time lag solenoid device adapted to make and break said main circuit, a main solenoid device in said main circuit for intermittently moving said display band, rotatable driving mechanism through which said display band is driven from said main solenoid device, an unlocking solenoid device connected in parallel in the main circuit with said main solenoid device, and adapted when energized and de-energized to unlock and lock said driving mechanism and permit and prevent movement of the display band, contact means operated by said main solenoid device during its driving stroke for short circuiting said unlocking solenoid device and thereby causing it to 'relock said driving mechanism against movement when the display band has been moved a predetermined amount, and contact breaking means associated with said main solenoid device for breaking said main circuit and deenergizing said time lag solenoid device.

7. In advertising and display apparatus of the type referred to, the combination of, a main electric circuit, a time lag solenoid device adapted to make and break said main circuit, a display band carrying the matter to be displayed or advertised, a main solenoid device in said main circuit adapted to move the display band intermittently, gearing and shafting through which the drive is communicated from said main solenoid to the display band, at least one detent adapted to engage and disengage said shafting for preventing and permitting movement of the display band totake place, and an unlocking solenoid device for intermittently causing said detent or detents so to engage and disengage.

8. In advertising and display apparatus of the type referred to, the combination of, a main electric circuit, a time lag solenoid device adapted to make and break said main circuit, a dash pot and piston for controlling the time of making of the main circuit by the time lag solenoid device, a display band carrying the matter to be displayed or advertised, a main solenoid device in said main circuit adapted to move the display band intermittently, gearing and shafting through which the drive is communicated from said main solenoidto the display band, at least one detent adapted to engage and disengage said shafting for preventing and permitting movement of the display band, and an unlocking solenoid device for intermittently causing said detent or detents to engage and disengage.

9. In advertising and display apparatus of the t pe referred to, the combination of, a main e ectric circuit, a time lag solenoid de vice adapted to make and breaksaid main circuit, a dash pot and piston and an adjustable air inlet and an air valve for said dash play band intermittently, gearing and shafting through which the drive is communicated from said main solenoid to the display band, at least one detent adapted to engage and disengage said shafting for preventing and permitting movement of the display band to take place, and an unlocking solenoid device'for intermittently causing said detent or detents so to engage and disengage.

' 10. In advertising and display apparatus of the type referred to, a display band carrying the matter to be displayed or advertised, a main solenoid for intermittently driving said'display band, a double-sided rack operated by said main solenoid, two gear trains one continuously engaged by each side of said rack and adapted to drive the display band in opposite directions, a unidirectional clutching device in each gear train automatically operated by the display band and adapted to connect and disconnect the drive through the respective gear train, whereby the direction of travel of the display band can be reversed after being Wound up in one direction.

11. In advertising and display apparatus of the type referred to, a display band carrying the matter to be displayed or advertised, a main solenoid with a plunger for intermittently driving said display band, a roller for driving said display band, a pair of driving shafts geared in opposite senses to said plunger of the main solenoid, apair of electro-magnets each adapted operatively to connect one of said driving shafts with said main solenoid, a pair of apertures in the display band each adapted to allow the magnetizing circuit of one of said electro-magnets to be completed when the band has been wound up in one direction, thereby causing the direction of movement of the band to be reversed.

12. In advertising or display apparatus of the type referred to, a display band adapted to be moved intermittently into a series of displaying"positions, a pair of magazine rollers between which the display band is wound, and means for compensating the movement of the magazine rollers in accordance with the amount of the display band wound on each, comprising, a friction clutch for each magazine roller, and a unidirectional clutch for each roller consisting of a driving drum, mounted freely with respect to the magazine roller and having peripheral tapering slots each carrying a. roller adapted to jam in the smallest part of the slot against the magazine roller to give a rigid drive between the driving drum and magazine roller when the magazine roller moves relative to the driving drum in one direction but adapted to float freely in the larger part of the slot and provide no driving connection between the magazine roller and driving drum When the magazine roller moves relative to the driving drum in the other direction.

In testimony whereof We aflix our signa tures.

JOHN WHITFIELD. DAVID BRANDER. 

